Blends of polycarbonate resin and a polyester resin, such as poly(butylene terephthalate), commonly phase separate into multiphase polymer compositions. See M. Okamoto et al., Polymer, 1994, Vol. 35, No. 2, pp. 257-261 and A. J. Brady et al., Polymer, 1994, Vol. 35, No. 17, pp. 3665-3672.
Certain recent disclosures exist in the art regarding the use of liquid crystalline polymers as additives for ternary polymer blends which also comprise polycarbonate and polyester resins. In U.S. Pat. No. 5,011,884 to B. Rosenau et al., for example, it is taught that polymeric molding compositions can be formed by adding from 20% to 70% of a thermotropic liquid crystalline polymer to a blend also comprising 10% to 50% of a polycarbonate resin and 10% to 50% of a polyester resin. More recent U.S. Pat. No. 5,262,473 to S. Cottis et al. teaches multiphase polymeric molding compositions comprising polycarbonate and polyester resins in which the blend also contains from 10% to 30% of a thermotropic liquid crystalline polymer which is preferably wholly aromatic in character.